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Going Green Cleaner fish like wrasse and cunners are helping salmon farms control sea lice. industry-wide will become clearer in the future, but the upside is obvious. For now, it's largely in the experimen- tal stages in Canada. Te four net pen sites in New Brunswick with cun- ners in the mix are under the close watch of Cooke Aqua- culture this year, says Nell Halse, VP-communications for the Blacks Harbor, N.B.- based company. Lab trials by fish-behavior scientists also show that the scavenger cunners, themselves consid- ered a pest by fishermen, are proving adept at removing lice that have latched on to salmon fins or bellies. Te use of wrasse for Send in the cleaners Can helper species effectively and economically combat sea lice at salmon farms? BY JAMES WRIGHT O f the roughly 25,000 swimming fish in each of four cir- cular net pens moored off the coast of New Brunswick, Canada, perhaps the most important ones contained therein aren't even salmon. For every 100 salm- on being fattened to market size for restaurants and su- permarkets internationally, there are about four or five cunners, a smaller fish that's been sent in to do a simple job: Feast on sea lice, the fin- fish aquaculture industry's most persistent pest. Tink of them as ladybugs control- ling aphids in a garden. Sea lice (Lepeophtheirus salmonis) have caused mil- lions of dollars in losses for salmon farms worldwide — as well as bad publicity for one of Canada's top super- market chains. One way to get rid of them is a pesticide. Slice (emamectin benzoate) and Salmosan are two com- mon and effective ones on the market, but aquaculture industry critics oppose the use of such substances, fear- ing dire consequences for other species, like lobsters, that live near the farm sites. Tere is, however, an al- ternative measure under 28 SeaFood Business December 2012 development that doesn't de- pend on chemicals and the early results are encourag- ing. Projects in Norway and Canada, at both the univer- sity and corporate levels, are turning to helper fish like the cunner (aka connor or ber- gall; Tautogolabrus adsper- sus) and wrasse to remove the lice that enter salmon farms; scientists at the University of Maine in Orono believe mussel rafts placed on the periphery of the finfish farms can also help, as larval lice have been found in mussel bellies and digestive tracts. Whether these so-called cleaner fish become a cost- effective method adopted such purposes is growing more common in Europe — Norwegian fish-farming giant Marine Harvest began breeding wrasse in 2009 — but the non-native species is not allowed in Canada; the native cunner, however, is. Cooke's immediate goal is to evaluate the feasibility of breeding cunners to avoid depleting wild stocks, and even to explore the potential of a side industry. "Sea lice have been around as long as salmon have been around," says Halse, adding "It's another tool in the toolbox to mitigate sea lice. Companies are looking at things other than therapeutants, which are costly." — Danny Boyce, researcher, Memorial University that Cooke employs multiple treatment regimens to van- quish the pesky parasites if and when they are detected. "Ide- ally, you want a suite of tools to treat your farms properly. Visit us online at www.seafoodbusiness.com Photos courtesy of Cooke Aquaculture